JP2016090544A - Strain detection plate and strain detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strain detection plate and a strain detection method capable of easily detecting strain about any direction on a surface of a detection object.SOLUTION: A strain detection plate includes: a metallic plate body 21 attached to a surface of a detection object; a circular pore 23 formed on the plate body 21; and a coating film layer 22 formed by applying stress coating medium on a surface of the plate body 21 on a circumference of the pore 23.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a strain detection plate and a strain detection method for detecting strain generated in a detection object due to a load such as an earthquake.

  In general, in a plant facility such as a nuclear power plant or a chemical plant, when an excessive load is applied to a structure such as a tank installed in the facility, damage to each part of the structure becomes a problem. For this reason, for example, when an earthquake or the like occurs, it is necessary to grasp the strain generated in the structure after the earthquake. In plant facilities, since there are a large number of target structures, it is preferable that the means for grasping the strain be simple, (A) a power supply is not required, (B) a wiring is not required, ( C) A means for satisfying what can be visually inspected is being sought.

  As a means for grasping this kind of strain, a surface strain detector having a measuring body that is made of a metal plate and has an opening formed so as to have at least one sharp open end is known (for example, Patent Document 1). This surface strain detector is attached to the surface of the object to be measured (detection object), and measures the cracks generated at the sharp opening end of the opening to reduce the strain generated in the object to be measured. It can be detected visually without any need.

JP 2010-256212 A

  However, since the conventional surface strain detector detects the strain generated in the measurement object due to the crack generated at the sharp opening end, the strain in the direction in which the sharp opening end is not formed cannot be detected. For this reason, there has been a problem that the strain generated in the measurement object cannot be detected in all directions (360 °) of the periphery of the measurement body (opening) attached to the measurement object.

  This invention is made | formed in view of the above, Comprising: It aims at providing the distortion | strain detection board and distortion | strain detection method which can detect distortion | strain easily about any direction of the surface of a detection target.

  In order to solve the above-described problems and achieve the object, the strain detection plate according to the present invention includes a metal plate attached to the surface of the detection target, a circular hole formed in the plate, And a coating film portion formed by applying a stress paint to the surface of the plate at the periphery of the hole.

  According to this configuration, since the coating film portion is formed by applying the stress paint to the periphery of the circular hole portion, it is possible to detect the strain generated in the detection target object by the crack generated in the coating film portion. it can. Furthermore, since the circular hole is formed in the plate body, it is possible to detect the distortion in any direction of the surface of the detection target without specifying the direction like the sharp opening end.

  In this configuration, the hole may be a perfect circular hole. According to this configuration, the maximum stress generated in the plate can be made uniform in the circumferential direction of the hole, so that any strain generated on the surface of the detection target can be accurately detected.

  The hole may be a long hole. According to this configuration, since the maximum stress generated in the plate body can be changed depending on the circumferential position of the hole, the sensitivity for detecting the strain can be adjusted.

  The plate may be formed of a material that is the same as the detection target or has a Young's modulus smaller than that of the detection target. According to this structure, the distortion | strain detection board attached to the detection target object can detect the distortion | strain of a detection target object correctly by changing similarly to a detection target object.

  Moreover, you may provide a predetermined space | interval in a plate body and may form a some hole part. According to this configuration, since the maximum stress generated in the plate can be changed according to the interval between the hole and the hole, the sensitivity for detecting strain can be adjusted.

  In addition, the strain detection method according to the present invention is a strain detection plate in which a circular hole is formed in a metal plate, and a coating material is provided by applying a stress paint to the surface of the plate at the periphery of the hole. Is attached to the surface of the detection object, and the direction or magnitude of the strain generated in the detection object is detected by a crack generated in the coating film portion of the strain detection plate. According to this configuration, strain can be easily detected in any direction on the surface of the detection target.

  According to the present invention, since the coating film portion is formed by applying the stress paint to the periphery of the circular hole portion, it is possible to detect the strain generated in the detection target object by the crack generated in the coating film portion. it can. Furthermore, since the circular hole is formed in the plate body, it is possible to detect the distortion in any direction of the surface of the detection target without specifying the direction like the sharp opening end.

FIG. 1 is a schematic view showing an example of an inspection object to which a strain detection plate according to this embodiment is attached. FIG. 2 is a plan view showing the strain detection plate according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 4 is a plan view for explaining the operation of the strain detection plate according to the first embodiment. FIG. 5 is a plan view for explaining the operation of the strain detection plate according to the second embodiment. FIG. 6 is a plan view for explaining the operation of the strain detection plate according to the third embodiment. FIG. 7 is a plan view for explaining the operation of the strain detection plate according to the fourth embodiment.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, this invention is not limited by the following embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a schematic diagram illustrating an example of a detection target to which a strain detection plate according to the present embodiment is attached. In FIG. 1, the code | symbol 10 is a solution tank which stores solutions, such as a chemical | medical solution, for example. The solution tank 10 is provided in a plant facility such as a chemical plant or a nuclear power plant, for example, and is installed on a floor 19 of the building of the plant facility. The solution tank 10 is integrally formed with a cylindrical body portion 11, an upper end plate 12 attached to the upper portion of the body portion 11, and a lower end plate 13 attached to the lower portion of the body portion 11. 13 is installed on the floor 19 by a plurality of leg portions (detection objects) 14 connected to 13. The lower end plate 13 of the solution tank 10 is connected to a lead-out pipe 15 for leading the solution in the solution tank 10. The lead-out pipe 15 is supported by a pipe support (detection target) 16 extending from the floor 19. Yes.

  In such a configuration, for example, when an earthquake occurs in the plant facility, a large load is applied to the leg portion 14 in the longitudinal direction (arrow Y direction) as the solution tank 10 swings in the direction indicated by the arrow X. As a result, the leg 14 is distorted. Similarly, a large load is applied to the pipe support 16 in the longitudinal direction (arrow Y direction), and the pipe support 16 is distorted. For this reason, after the earthquake has subsided, it is necessary to inspect for the presence or absence of distortion generated in the legs 14 and the pipe supports 16 of the solution tank 10. In this configuration, in order to easily detect the strain generated in the leg portion 14 and the pipe support 16 of the solution tank 10 visually, the strain detection plates 20 and 20 are respectively provided on the leg portion 14 and the pipe support 16 of the solution tank 10. Is attached. Next, the strain detection plate will be described.

[First Embodiment]
FIG. 2 is a plan view showing the strain detection plate according to the first embodiment, and FIG. 3 is a cross-sectional view taken along the line AA of FIG. As shown in FIG. 2, the strain detection plate 20 includes, for example, a regular hexagonal metal plate 21, and a perfectly circular hole 23 is formed at the center of the plate 21. . As shown in FIG. 3, a coating layer (coating portion) 22 to which a stress paint (described later) is applied is formed on the surface 21 </ b> A of the plate body 21.

  The plate body 21 is attached to the leg portion 14 or the pipe support 16 by attaching an adhesive (not shown) or the like to the back surface 21B side. In this case, it is desirable to apply an adhesive to the entire back surface 21B so that the plate body 21 and the leg portion 14 or the pipe support 16 are integrated. The plate 21 is made of, for example, the same metal material as the base material of the legs 14 to be attached or a metal material softer (small Young's modulus) than the base material. According to this configuration, for example, the strain detection plate 20 affixed to the leg portion 14 can detect the strain of the leg portion 14 accurately by being deformed in the same manner as the leg portion 14. In the present embodiment, the outer peripheral edge of the plate body 21 is formed in a regular hexagonal shape, but other shapes may be adopted, and for example, the plate body 21 may be formed in a square shape or a circular shape.

  The coating layer 22 is formed by applying a stress paint. The stress paint is a paint having very brittle properties for the purpose of analyzing the stress generated in the object. As the stress paint, CRUX (registered trademark: manufactured by Mark Tech Co., Ltd.) or Stress Mark 2 (manufactured by Tech Tech Sales Co., Ltd.) can be used. This type of stress paint can be easily applied in an aerosol type and can be easily dried without drying, so that the coating layer 22 can be easily formed. When a stress is applied to the plate body 21, the coating film layer 22 is cracked by this stress, so that the presence or absence of strain can be visually detected by this crack. The coating layer 22 is preferably coated with a stress coating so that the film thickness is about 0.1 mm.

  The strain measurement by the strain detection plate 20 is performed as follows. First, the strain detection plate 20 is attached to the surfaces of the leg portion 14 and the pipe support 16 of the solution tank 10 using an adhesive. In this state, when an earthquake occurs in the plant facility, inspection of each device in the plant facility is performed when the plant facility is restarted after the earthquake. In the inspection work, paying attention to the strain detection plate 20 affixed to the surfaces of the legs 14 and the pipe support 16, the maximum strain is detected by a crack generated in the coating layer 22.

  Specifically, as shown in FIG. 4, when a tensile stress F is applied to the strain detection plate 20, the stress generated in the strain detection plate 20 is perpendicular to the tensile stress F and passes through the hole center 24. The maximum is at the edge of the hole 23 intersecting with, and the maximum stress is three times the tensile stress F. Therefore, in the strain detection plate 20, cracks (cracks) K are generated in the regions 25 on both sides of the hole 23 located on the two-dot chain line 24, and a clear crack pattern is drawn on the coating layer 22. The direction of strain generated in the leg portion 14 and the pipe support 16 of the solution tank 10 can be detected by the location where the crack K occurs and the direction in which the crack K propagates. The amount of strain (strain magnitude) is related to the number and length of cracks K. For this reason, for example, a strain (stress) of a predetermined magnitude is generated on the strain detection plate 20 by an experiment or the like, and a correlation between the strain amount and the number and length of the cracks K is obtained in advance. deep. Then, the maximum strain amount can be detected by comparing with the number and length of the cracks K actually generated. At this time, it is preferable to verify the maximum strain amount by collating with the measurement result of the seismometer installed in the plant facility.

  In the first embodiment, since the hole 23 is formed in a perfect circle shape, the maximum stress generated at the edge of the hole 23 regardless of the direction from which the tensile stress F is applied to the strain detection plate 20. The values of are the same. For this reason, since the strain detection plate 20 having the same sensitivity can be formed with respect to the strain generated in any direction, the strain in any direction generated in the leg portion 14 or the pipe support 16 is accurately detected. can do.

[Second Embodiment]
Although the hole 23 according to the first embodiment described above has a perfect circle shape, the hole may not be a perfect circle as long as it is circular. In the second embodiment, the strain detection plate 30 includes an elliptical (long hole shape) hole 33. In the strain detection plate 30 according to the second embodiment, the shape of the hole 33 is the same as that of the strain detection plate 20 except for the shape of the hole 33, and thus description thereof is omitted.

  As shown in FIG. 5, the strain detection plate 30 has an elliptical hole 33. In the strain detection plate 30 having the elliptical hole 33, when a tensile stress F is applied in the direction along the short axis of the hole 33, the stress generated in the strain detection plate 30 is long and perpendicular to the tensile stress F. It becomes the maximum at the edge of the hole 33 intersecting the two-dot chain line 34 passing through the axis. This maximum stress is related to the length of the minor axis and the major axis. For example, if the ratio of the length of the minor axis to the major axis is 1: 2, the maximum stress is five times the tensile stress F.

  For this reason, in the strain detection plate 30, cracks (cracks) K are generated in the regions 35 on both sides of the hole 33 located on the two-dot chain line 34, and a clear crack pattern is drawn on the coating layer 22. In this 2nd Embodiment, since the maximum stress which arises in the distortion | strain detection board 30 can be changed with the circumferential direction position of the hole 33 by making the hole 33 elliptical, the sensitivity at the time of detecting a distortion is adjusted. be able to. Specifically, when the ratio of the length of the minor axis to the major axis is 1: 2, the maximum stress is five times the tensile stress F. For this reason, when the tensile stress F is applied in the direction along the minor axis of the hole 33, the sensitivity when detecting the strain can be increased. In the second embodiment, since the sensitivity when detecting strain can be changed by changing the ratio of the length between the short axis and the long axis, for example, the ratio of the length between the short axis and the long axis is changed. By providing a plurality of changed strain detection plates 30, the maximum strain amount can be accurately detected.

[Third Embodiment]
In the first and second embodiments described above, the holes 23 and 33 are single, but the strain detection plate 40 according to the third embodiment includes a plurality (two) of holes 43 and 43. The strain detection plate 40 according to the third embodiment is the same as the strain detection plate 20 except for the number and positions of the holes 43, and thus the description thereof is omitted.

  As shown in FIG. 6, the strain detection plate 40 has two holes 43 and 43 arranged side by side along the center line 44 of the strain detection plate 40. The hole 43 has a perfect circular shape with a radius ρ (diameter 2ρ), and the distance between the centers of the holes 43 and 43 (also referred to as the distance between the holes) is set to 2P. When a tensile stress F is applied to the strain detection plate 40 along the center line 44, the stress generated in the strain detection plate 40 is maximized in the region 46 between the holes 43 and 43. This maximum stress is related to the diameter 2ρ of the hole 43 and the distance 2P between the holes. For example, if the ratio P / ρ between the diameter 2ρ and the distance 2P between the holes is 1.337, the maximum stress is It is about 3.5 times the tensile stress F.

  For this reason, in the strain detection plate 40, a crack (crack) K is generated in the region 46 between the holes 43, 43 in the direction perpendicular to the center line 44, and a clear crack pattern is drawn on the coating layer 22. In the third embodiment, since the maximum stress generated in the strain detection plate 40 can be changed by changing the distance 2P between the holes with respect to the diameter 2ρ of the hole 43, the sensitivity when detecting the strain can be adjusted. it can. Specifically, when the ratio P / ρ between the diameter 2ρ and the inter-hole distance 2P is 1.061, the maximum stress is about 6.7 times the tensile stress F. For this reason, the sensitivity at the time of detecting a strain can be changed by changing the distance 2P between the holes with respect to the diameter 2ρ. For example, by providing a plurality of strain detection plates 40 in which the distance 2P between the holes with respect to the diameter 2ρ is changed, The maximum strain can be accurately detected.

[Fourth Embodiment]
The strain detection plate 50 according to the fourth embodiment includes a plurality (four) of holes 53. The strain detection plate 50 according to the fourth embodiment is the same as the strain detection plate 20 except for the number and positions of the holes 53, and thus the description thereof is omitted.

  As shown in FIG. 7, the strain detection plate 50 has two holes 53 and 53 arranged side by side along the center lines 54 and 55 of the strain detection plate 50. That is, the two holes 53, 53 arranged along the center line 54 are arranged equidistant from the center line 55 across the center line 55 orthogonal to the center line 54, and are arranged along the center line 55. The holes 53 and 53 are arranged equidistant from the center line 54 with the center line 54 interposed therebetween. Each of the holes 53 has a perfect circular shape with a radius ρ (diameter 2ρ), and the holes 53 and 53 arranged on one center line 54 and the holes 53 and 53 arranged on the other center line 55. The center-to-center distances (also referred to as hole-to-hole distances) are each set to 2P.

  For example, when a tensile stress F is applied to the strain detection plate 50 along one center line 54, the stress generated in the strain detection plate 50 is a hole 53, 53 whose center distance is set to 2P. It becomes the maximum in the area | region 56 between. This maximum stress is related to the diameter 2ρ of the hole 53 and the distance 2P between the holes. For example, if the ratio P / ρ between the diameter 2ρ and the distance 2P between the holes is 0.5, the maximum stress is It becomes about 6 times the tensile stress F.

  For this reason, in the strain detection plate 50, a crack (crack) K is generated in the region 56 between the holes 53, 53 in a direction perpendicular to the line connecting the holes 53, 53, and the coating layer 22 is clear. A crack pattern is drawn. In the fourth embodiment, since the maximum stress generated in the strain detection plate 50 can be changed by changing the inter-hole distance 2P with respect to the diameter 2ρ of the hole 53, it is possible to adjust the sensitivity when detecting the strain. it can. Specifically, when the ratio P / ρ between the diameter 2ρ and the inter-hole distance 2P is 0.75, the maximum stress is about 10 times the tensile stress F. For this reason, the sensitivity at the time of detecting strain can be changed by changing the distance 2P between the holes with respect to the diameter 2ρ. For example, by providing a plurality of strain detection plates 50 in which the distance 2P between the holes with respect to the diameter 2ρ is changed, The maximum strain can be accurately detected.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. In the above-described embodiment, the leg portion 14 and the pipe support 16 of the solution tank 10 have been described as an example of the detection target to which the strain detection plate is attached. For example, the strain detection plate is attached inside the nacelle of a windmill for wind power generation. Also good. Specifically, a strain detection plate is affixed to the rotating shaft of a windmill housed in the nacelle, and after operating for a predetermined period in this state, the strain detecting plate is observed to generate the rotational shaft of the windmill during operation. Maximum strain can also be detected.

DESCRIPTION OF SYMBOLS 10 Solution tank 11 Trunk part 12 Upper end plate 13 Lower end plate 14 Leg part (detection target object)
15 Lead pipe 16 Piping support (detection target)
19 floor 20, 30, 40, 50 strain detection plate 21 plate body 21A surface 21B back surface 22 coating layer (coating part)
23, 33, 43, 53 Hole 25, 35, 46, 56 Region K Crack (crack)
2P Distance between holes 2ρ Diameter

Claims (7)

A metal plate attached to the surface of the detection object;
A circular hole formed in the plate,
A strain detection plate comprising: a coating film portion formed by applying a stress paint to a surface of the plate body at a peripheral edge of the hole portion.   The strain detection plate according to claim 1, wherein the direction or magnitude of the strain generated in the detection object is detected by a crack generated in the coating film portion.   The strain detection plate according to claim 1, wherein the hole is a perfect circular hole.   The strain detection plate according to claim 1, wherein the hole is a long hole.   5. The strain detection plate according to claim 1, wherein the plate body is made of a material that is the same as the detection object or has a Young's modulus smaller than that of the detection object. .   The strain detection plate according to any one of claims 1 to 5, wherein a plurality of the hole portions are formed at predetermined intervals in the plate body.   A circular hole is formed in a metal plate, and a strain detection plate provided with a coating film portion by applying a stress coating to the surface of the plate at the periphery of the hole is attached to the surface of the detection object, A strain detection method, comprising: detecting a direction or magnitude of a strain generated in the detection target object by a crack generated in the coating film portion of the strain detection plate.

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